WO2022091948A1

WO2022091948A1 - Aluminum alloy for sliding component, and sliding component

Info

Publication number: WO2022091948A1
Application number: PCT/JP2021/038978
Authority: WO
Inventors: 匠丸山
Original assignee: 昭和電工株式会社
Priority date: 2020-10-30
Filing date: 2021-10-21
Publication date: 2022-05-05
Also published as: EP4239091A4; US20230399723A1; JP7517081B2; JP2022072575A; CN116529404A; EP4239091A1

Abstract

This aluminum alloy for a sliding component contains 8.0-12.0 mass% of Si, 0.8-1.1 mass% of Cu, 0.4-0.6 mass% of Mg, 0.30-0.60 mass% of Mn, 0.01-0.03 mass% of Cr, 0.10-0.30 mass% of Fe, 0.0005-0.0050 mass% of Ca and 0.00005-0.03000 mass% of Sr, with the remainder comprising Al and unavoidable impurities. The ratio of the content of Sr relative to the content of Ca (Sr/Ca) falls within the range 0.01-30. The aluminum alloy has a tensile strength at 25ºC of 330-380 MPa, contains 1 mass% or more of Cu, does not contain two or more crystallized products having a circle-equivalent diameter of more than 5 µm per 1182 µm2, and does not contain two or more Cr-containing intermetallic compounds having a length of 8 µm or more per 1182 µm2.

Description

Aluminum alloy for sliding parts and sliding parts

The present invention relates to aluminum alloys for sliding parts and sliding parts.
This application claims priority based on Japanese Patent Application No. 2020-182092 filed in Japan on October 30, 2020, the contents of which are incorporated herein by reference.

Due to the demand for improved fuel efficiency in the automobile industry in recent years, various components used in automobiles, such as compressors for automobile air conditioners, are also required to be lighter and more sophisticated. There are various types of compressors for air conditioners, but scroll type compressors are widely used as compressors for automobile air conditioners.

The scroll type compressor has a pair of spiral type sliding parts (scrolls), one sliding part (fixed scroll) is fixed, and the other sliding part (swivel scroll) is swiveled to form a pair. Compressed air is generated by reducing the volume of the space formed between the sliding parts. The sliding parts used in the scroll type compressor having such a configuration are required to have excellent tensile strength as well as wear resistance during sliding. Further, the sliding parts of the scroll type compressor used for the air conditioner of an automobile are also required to have excellent heat resistance so that they can be used in a harsh environment under a high temperature atmosphere.

In order to reduce the weight of the sliding parts of the scroll type compressor, it is preferable that the material of the sliding parts has a large specific strength, which is the ratio of the strength to the weight. Therefore, an aluminum alloy is generally used as a material for sliding parts of a scroll type compressor. As the aluminum alloy, an Al—Si based aluminum alloy is used from the viewpoint of tensile strength, wear resistance, and heat resistance. Further, in order to improve the wear resistance of the sliding parts, the surface of the sliding parts is anodized (anodized) to form a hard alumite film on the surface of the sliding parts. ing.

In order to improve the tensile strength of aluminum alloys, it is being studied to add metal elements such as Cu and Mg to Al—Si aluminum alloys (Patent Documents 1 and 2). On the other hand, it is known that when an additive metal such as Cu or Mg, particularly Cu, is added to an aluminum alloy at a high concentration, the growth of the alumite film due to the anodizing treatment is inhibited and the formability of the alumite film is lowered (patented). Document 3).

Japanese Unexamined Patent Publication No. 2005-281742 Japanese Unexamined Patent Publication No. 8-28493 Japanese Unexamined Patent Publication No. 2005-330560

In order to improve the tensile strength of the aluminum alloy, it is effective to add metal elements such as Cu and Mg to the Al—Si based aluminum alloy. However, when the amount of the metal element added is large, coarse crystallization or an intermetal compound composed of two or more kinds of metals is generated in the aluminum alloy, and the tensile strength of the aluminum alloy is lowered or alumite. The formability of the film may decrease. Therefore, it is difficult to obtain an aluminum alloy having excellent both tensile strength and alumite film forming property.

The present invention has been made in view of the above-mentioned technical background, and an object of the present invention is to provide an aluminum alloy for sliding parts and sliding parts having excellent tensile strength and formability of an alumite film. do.

In order to achieve the above object, as a result of diligent research, the present inventor added Cu, Mg, Mn, Cr, Fe, Ca, and Sr elements to the Al—Si aluminum alloy in a specific amount. As a result, it has been found that it is possible to obtain an aluminum alloy having a high tensile strength and a small amount of coarse crystallization and intermetallic compounds mixed in. Then, it was confirmed that the aluminum alloy can form a hard alumite film on the surface by the anodizing treatment, and the present invention was completed. That is, the present invention provides the following means.
The first aspect of the present invention provides the aluminum alloy described in the following [1].

[1] Si is in the range of 8.5% by mass or more and 10.5% by mass or less, Cu is in the range of 0.8% by mass or more and 1.1% by mass or less, and Mg is in the range of 0.4% by mass or more and 0.6. Mn is in the range of 0.30% by mass or more and 0.60% by mass or less, Cr is in the range of 0.01% by mass or more and 0.03% by mass or less, and Fe is in the range of 0.10% by mass. Ca is contained in the range of 0.0005% by mass or more and 0.0050% by mass or less, and Sr is contained in the range of 0.00005% by mass or more and 0.03000% by mass or less. The balance is Al and unavoidable impurities, the ratio of Sr content to Ca content is in the range of 0.01 or more and 30 or less, and the tensile strength at 25 ° C is in the range of 330 MPa or more and 380 MPa or less. In 1182

μm

2, 2 or more Cr-containing intermetal compounds having a length of 8 μm or more, containing 1% by mass or more of Cu and not containing ² or more crystals having a circle equivalent diameter of more than 5 μm per 1182 μm ² . An aluminum alloy for sliding parts, which is characterized by not containing more than one.
The aluminum alloy preferably contains Si in an amount of 8.5% by mass or more and 12.0% by mass or less.

The first aspect of the present invention preferably has the following characteristics [2].
[2] The aluminum alloy for sliding parts according to the above [1], which does not contain two or more primary crystal Si grains having a diameter equivalent to a circle exceeding 10 μm per 4726 μm ² .
A second aspect of the present invention provides the sliding component described in [3] below.
[3] A sliding component made of the aluminum alloy for the sliding component according to the above [1] or [2].
The second aspect of the present invention preferably has the following features [4] to [8]. It is also preferable to combine two or more of these features.
[4] The sliding component according to the above [3], which is a forged product.
[5] The sliding component according to the above [3] or [4], wherein the surface is provided with an alumite film having a Vickers hardness of 400 HV or more.
[6] The sliding component according to any one of the above [3] to [5], which is a sliding component of a compressor.
[7] The sliding component according to any one of the above [3] to [5], which is a sliding component of a scroll type compressor.
[8] The sliding component according to any one of the above [3] to [5], which is a sliding component of an electric scroll type compressor.

According to the present invention, it is possible to provide an aluminum alloy for sliding parts and sliding parts having excellent tensile strength and formability of an alumite film.

It is a flow figure which shows the example of the manufacturing method of the sliding component which concerns on one Embodiment of this invention. It is a schematic perspective view which shows an example of the aluminum alloy (casting article) for sliding parts which concerns on one Embodiment of this invention. It is a schematic perspective view which shows an example of the sliding component (forged article) which concerns on one Embodiment of this invention.

Hereinafter, preferred examples of the aluminum alloy for sliding parts and the sliding parts according to the embodiment of the present invention will be described in detail.
In addition, the drawings used in the following description may schematically show the characteristic parts for convenience in order to make the features easy to understand, and the dimensional ratios of each component are not always the same as the actual ones. not.
The present embodiment will be specifically described in order to better understand the gist of the invention, and is not limited to the present invention unless otherwise specified. It is possible to change, add, omit, replace, etc. the number, material, quantity, shape, numerical value, ratio, position, configuration, etc. within the range not deviating from the gist of the present invention.

<Aluminum alloy for sliding parts>
The aluminum alloy for sliding parts of the present embodiment contains Si in the range of 8.0% by mass or more and 12.0% by mass or less, Cu in the range of 0.8% by mass or more and 1.1% by mass or less, and Mg. In the range of 0.4% by mass or more and 0.6% by mass or less, Mn in the range of 0.30% by mass or more and 0.60% by mass or less, Fe in the range of 0.10% by mass or more and 0.30% by mass or less. Among them, Cr is in the range of 0.01% by mass or more and 0.03% by mass or less, Ca is in the range of 0.0005% by mass or more and 0.0050% by mass or less, and Sr is 0.00005% by mass or more and 0.03000% by mass. It is contained in the range of% or less, and the balance is Al and unavoidable impurities. Further, in the aluminum alloy for sliding parts of the present embodiment, the ratio of the Sr content to the Ca content, Sr / Ca, is in the range of 0.01 or more and 30 or less. Further, the aluminum alloy for sliding parts of the present embodiment has a tensile strength in the range of 330 MPa or more and 380 MPa or less at 25 ° C. Furthermore, the aluminum alloy for sliding parts of the present embodiment contains 1% by mass or more of Cu, does not contain two or more crystallized substances having a circle equivalent diameter of more than 5 μm per 1182 μm ² , and has a length of 8 μm or more. It is said that two or more Cr-containing intermetallic compounds are not contained in 1182 μm ² . Further, the aluminum alloy for sliding parts of the present embodiment does not have to contain two or more primary crystal Si grains having a diameter equivalent to a circle of more than 10 μm per 4726 μm ² .

(Si: 8.0% by mass or more and 12.0% by mass or less)
Si (component) has an action of improving the tensile strength of the aluminum alloy. However, if Si is excessively added to the aluminum alloy, the tensile strength of the aluminum alloy may decrease due to the crystallization of coarse primary crystal Si grains. Further, the primary crystal Si grains may reduce the formability of the alumite film.
If the Si content is less than 8.0% by mass, it may be difficult to obtain the effect of improving the tensile strength by Si. On the other hand, if the Si content exceeds 12.0% by mass, coarse primary Si grains may easily crystallize. For the above reasons, in the present embodiment, the Si content is in the range of 8.0% by mass or more and 10.5% by mass or less. The Si content is more preferably in the range of 9.0% by mass or more and 10.5% by mass or less. The Si content can be arbitrarily selected as long as it is within the above range, and for example, 8.20% by mass to 12.00% by mass, 8.50% by mass to 12.00% by mass, or 9.00% by mass or more. It may be 11.50% by mass, 9.50% by mass to 11.00% by mass, 10.00% by mass to 11.5% by mass, or the like.

(Cu: 0.8% by mass or more and 1.1% by mass or less)
Cu (component) has an action of improving the tensile strength of the aluminum alloy. Cu is a G.I. P. Form a zone. G. P. Zones are aggregates of solute atoms that appear in the matrix during aging of age-hardened alloys. This G. P. The zone (Guinier-Preston zone) becomes the intermediate phase, which contributes to the improvement of the tensile strength of the aluminum alloy.
If the Cu content is less than 0.8% by mass, it may be difficult to obtain the effect of improving the tensile strength of Cu. On the other hand, if the Cu content exceeds 1.1% by mass, the formability of the alumite film may decrease. For the above reasons, in the present embodiment, the Cu content is in the range of 0.8% by mass or more and 1.1% by mass or less. The Cu content is preferably in the range of 0.9% by mass or more and 1.0% by mass or less. The Cu content can be arbitrarily selected as long as it is within the above range, and for example, 0.80% by mass to 1.10% by mass, 0.85% by mass to 1.05% by mass, or 0.90% by mass to 0.90% by mass. 1.00. It may be mass% or 0.93 mass% to 0.98 mass%.

(Mg: 0.4% by mass or more and 0.6% by mass or less)
Mg (component) has an action of improving the tensile strength of the aluminum alloy in the same manner as Cu. Mg forms a compound containing Si and Cu in an aluminum alloy. Precipitation of this compound as the Q phase contributes to the improvement of the tensile strength of the aluminum alloy.
If the Mg content is less than 0.4% by mass, it may be difficult to obtain the effect of improving the tensile strength by Mg. On the other hand, if the Mg content exceeds 0.6% by mass, the effect of improving the tensile strength by Mg may decrease. Therefore, in the present embodiment, the Mg content is in the range of 0.4% by mass or more and 0.6% by mass or less. The Mg content is preferably in the range of 0.45% by mass or more and 0.55% by mass or less. The Mg content can be arbitrarily selected as long as it is within the above range, for example, 0.40% by mass or more and 0.60% by mass or less, 0.43% by mass or more and 0.58% by mass or less, or 0.50% by mass. It may be% or more and 0.53% by mass or less.

(Mn: 0.30% by mass or more and 0.60% by mass or less)
Mn (component) has an action of improving the tensile strength of the aluminum alloy. Mn contributes to the improvement of the tensile strength of the aluminum alloy by forming fine granular crystallized substances containing an Al—Mn—Si intermetallic compound or the like in the aluminum alloy.
If the Mn content is less than 0.30% by mass, it may be difficult to obtain the effect of improving the tensile strength by Mn. On the other hand, if the Mn content exceeds 0.60% by mass, the above-mentioned intermetallic compound may form coarse crystallization and reduce the tensile strength of the aluminum alloy. For the above reasons, in the present embodiment, the Mn content is in the range of 0.30% by mass or more and 0.60% by mass or less. The Mn content is preferably in the range of 0.35% by mass or more and 0.55% by mass or less. The Mn content can be arbitrarily selected as long as it is within the above range, and for example, 0.38% by mass to 0.53% by mass, 0.40% by mass to 0.50% by mass, or 0.43% by mass to 0.43% by mass. It may be 0.47% by mass.

(Cr: 0.01% by mass or more and 0.03% by mass or less)
Cr (component) has an action of improving the mechanical properties of the aluminum alloy. Cr crystallizes as a fine Cr-containing metal-to-metal compound containing an Al—Fe-Cr metal-to-metal compound in the aluminum alloy, thereby contributing to the improvement of the mechanical properties of the aluminum alloy.
If the Cr content is less than 0.01% by mass, it may be difficult to obtain the effect of improving the tensile strength by Cr. On the other hand, if the Cr content exceeds 0.03% by mass, the Cr-containing intermetallic compound may form coarse crystallization and reduce the tensile strength of the aluminum alloy. For the above reasons, in the present embodiment, the Cr content is in the range of 0.01% by mass or more and 0.03% by mass or less. The Cr content is preferably in the range of 0.015% by mass or more and 0.02% by mass or less. The Cr content can be arbitrarily selected as long as it is within the above range, and for example, 0.013% by mass to 0.028% by mass, 0.018% by mass to 0.026% by mass, or 0.020% by mass to 0.020% by mass. It may be 0.024% by mass. )

(Fe: 0.10% by mass or more and 0.30% by mass or less)
Fe (component) has an action of improving the tensile strength of the aluminum alloy. Fe is crystallized as a fine crystallized product containing an Al—Fe—Si intermetallic compound, an Al—Cu—Fe intermetallic compound, an Al—Mn—Fe intermetallic compound, etc. in an aluminum alloy to form an aluminum alloy. Contributes to the improvement of mechanical properties of aluminum.
If the Fe content is less than 0.10% by mass, it may be difficult to obtain the effect of improving the tensile strength by Fe. On the other hand, if the Fe content exceeds 0.30% by mass, the intermetallic compound may form coarse crystallization and reduce the tensile strength of the aluminum alloy. For the above reasons, in the present embodiment, the Fe content is in the range of 0.10% by mass or more and 0.30% by mass or less. The Fe content is preferably in the range of 0.15% by mass or more and 0.25% by mass or less. The Fe content can be arbitrarily selected as long as it is within the above range, and may be, for example, 0.13% by mass to 0.27% by mass or 0.17% by mass to 0.20% by mass.

(Ca: 0.0005% by mass or more and 0.0050% by mass or less, Sr: 0.00005% by mass or more and 0.03000% by mass or less, Sr / Ca: 0.01 or more and 30 or less)
Ca and Sr each have an action of suppressing the crystallization of primary Si grains.
Comparing Ca and Sr, Sr has a higher effect of suppressing eutectic Si grains, that is, an effect of improving corrosion resistance. Further, when Ca and Sr are added in combination, the improvement efficiency due to the addition of Ca may decrease. Therefore, it is necessary to adjust the ratio of the content of Ca and Sr together with the content of Ca and Sr. For the above reasons, in the present embodiment, the Ca content is in the range of 0.0005% by mass or more and 0.0050% by mass or less, and the Sr content is in the range of 0.00005% by mass or more and 0.03000% by mass or less. , The ratio of Sr content to Ca content Sr / Ca is in the range of 0.01 or more and 30 or less. The Ca content is preferably in the range of 0.0005% by mass or more and 0.0020% by mass or less. The Ca content may be 0.0008% by mass or more and 0.0015% by mass or less, or 0.0010% by mass or more and 0.0013% by mass or less, if necessary. The content of Sr is preferably 0.00005% by mass or more and 0.0200% by mass or less. The content of Sr may be 0.0005% by mass or more and 0.0150% by mass or less, or 0.0008% by mass or more and 0.0100% by mass or less, if necessary. The ratio of the Sr content to the Ca content Sr / Ca may be in the range of 0.01 or more and less than 2.2, or in the range of 2.2 or more and 25 or less, if necessary. It may be in the range of 0.10 or more and 23 or less, in the range of 0.50 or more and 8.0 or less, or in the range of 1.0 or more and 5.0 or less. It may be in the range of 5.0 or more and 20 or less, or in the range of 10.0 or more and 15 or less.

(Inevitable impurities)
The unavoidable impurities are impurities that are inevitably mixed with the aluminum alloy from the raw material or the manufacturing process of the aluminum alloy. In the aluminum alloy of the present embodiment, the mixing amount of each element of Zn, Ni, Zr, and Ti preferably does not exceed 0.5% by mass in the total content of each of these elements. When the total content of each of the above elements exceeds 0.5% by mass, each element crystallizes before the Al matrix to form coarse crystallization, and the ductility of the aluminum alloy becomes small. , The tensile strength may decrease. The amount of unavoidable impurities can be arbitrarily selected as long as it is within the above range, for example, less than 0.50% by mass, 0.40% by mass or less, 0.30% by mass or less, 0.20% by mass or less, and the like. , 0.10% by mass or less, 0.05% by mass or less, 0.01% by mass or less, or 0.001% by mass or less.

(Tensile strength at 25 ° C: within the range of 330 MPa or more and 380 MPa or less)
The aluminum alloy of the present embodiment has a tensile strength at 25 ° C. in the range of 330 MPa or more and 380 MPa or less. The tensile strength is a value measured using a JIS No. 4 tensile test piece in accordance with the provisions of JIS Z2241: 2011 (Metallic Material Tensile Test Method). The tensile strength can be arbitrarily selected as long as it is within the above range, and may be, for example, 340 MPa or more and 370 MPa or less, or 350 MPa or more and 360 MPa or less.

(Crystal containing 1% by mass or more of Cu and having a diameter equivalent to a circle exceeding 5 μm: 1182 μm does not contain ² or more per 2)
If the circle-equivalent diameter of the Cu-based crystallized product containing 1% by mass or more of Cu exceeds 5 μm, the formation of an alumite film by the anodizing treatment may be hindered. Therefore, in the present embodiment, it is said that two or more coarse Cu-based crystals having a circle-equivalent diameter of more than 5 μm are not contained per 1182 μm ² . The number of coarse Cu-based crystals per 1182 μm ² is preferably 1 or less, and more preferably does not contain coarse Cu-based crystals. When the coarse Cu-based crystallized material is not contained, the maximum circle-equivalent diameter of the Cu-based crystallized material contained in the aluminum alloy is preferably 3 μm or less, and more preferably 1 μm or less.

The circle-equivalent diameter and number of Cu-based crystals are, for example, FE-SEM (field emission scanning electron microscope) in the range of 30.47 μm × 38.97 μm (= 1182 μm ² ) of the cross section of an aluminum alloy. ) / EDS (Energy Dispersive X-ray Analyzer) can be used for observation. That is, by performing elemental analysis using EDS, Cu-based crystals containing 1% by mass or more of Cu are detected, and the circle-equivalent diameter and number of the detected Cu-based crystals are measured by SEM images. It can be measured by doing. Examples of the crystallized product include, but are not limited to, Al-Cu-Mg-Si.

(Cr-containing intermetallic compound having a length of 8 μm or more: 2 or more are not contained per 1182 μm ² ) A Cr-containing intermetallic compound having a length of 8 μm or more may reduce the tensile strength of the aluminum alloy. Therefore, in the present embodiment, it is said that two or more coarse Cr-containing intermetallic compounds having a length of 8 μm or more are not contained per 1182 μm ² . The number of coarse Cr-containing intermetallic compounds per 1182 μm ² is preferably 1 or less, and more preferably not containing coarse Cr-containing intermetallic compounds. When the coarse Cr-containing intermetallic compound is not contained, the maximum length of the Cr-containing intermetallic compound contained in the aluminum alloy is preferably 6 μm or less, and more preferably 4 μm or less.
The length and number of Cr-containing intermetallic compounds are the same as in the case of the Cu-based crystallized product described above, in the range of 1182 μm ² of the cross section of the aluminum alloy, using FE-SEM / EDS, the Cr-containing intermetallic compound. Is detected, and the length and number of the detected Cr-containing intermetallic compounds can be measured by measuring with an SEM image. Examples of the intermetallic compound include, but are not limited to, Al—Cr—Si. The difference between the Cr-containing intermetallic compound and the Cu-based crystallized product includes the shape of the Cr-containing intermetallic compound and the like.

(Primary Si grains with a circle-equivalent diameter of more than 10 μm: 2 or more per 4726 μm ² ) Coarse primary Si grains with a circle-equivalent diameter of more than 10 μm may hinder the formation of an anodized film. be. Therefore, in the present embodiment, it is said that two or more coarse primary crystal Si grains having a diameter equivalent to a circle exceeding 10 μm are not contained per 4726 μm ² . The number of coarse primary Si grains is preferably 1 or less, and more preferably no coarse primary Si grains are contained. When the coarse primary Si grains are not contained, the diameter corresponding to the maximum circle of the primary Si grains contained in the aluminum alloy is preferably 8 μm or less, and more preferably 4 μm or less.
The equivalent circle diameter and number of primary crystal Si grains can be measured by observing the cross section of the aluminum alloy in the range of 60.9 μm × 77.6 μm (= 4726 μm ² ) using FE-SEM / EDS. .. The primary Si grains consist only of Si.

<Sliding parts>
The sliding parts of the present embodiment are made of the above-mentioned aluminum alloy for sliding parts of the present embodiment. The sliding component of this embodiment may be a forged product.
The sliding component of the present embodiment may be provided with an alumite film having a Vickers hardness of 400 HV or more on the surface thereof. The alumite film can be formed by anodizing. The film thickness of the alumite film is preferably in the range of 4 μm or more and 100 μm or less. The Vickers hardness of the alumite film is preferably in the range of 400 HV or more and 450 HV or less. The Vickers hardness can be measured according to the Vickers hardness test-test method described in JIS Z 2244.

Next, a preferable example of the method for manufacturing the sliding parts of the present embodiment will be described.
FIG. 1 is a flow chart showing an example of a method for manufacturing a sliding component according to an embodiment of the present invention. As shown in FIG. 1, the method for manufacturing a sliding component of the present embodiment includes a molten metal forming step S01 for obtaining a molten metal of an aluminum alloy, a casting step S02 for obtaining a cast product by casting the molten metal, and a cast product. It has a forging step S05 for forging to obtain a forged product. A homogenization heat treatment step S03 and a cutting step S04 may be performed between the casting step S02 and the forging step S05. Further, after the forging step S05, the solution treatment step S06, the quenching step S07, the aging treatment step S08, and the shot peening step S09 may be performed.

(Melted metal forming step S01)
In the molten metal forming step S01, raw materials such as Al source, Si source, Cu source, Mg source, Mn source, Fe source, Cr source, Ca source and Sr source are mixed so as to form the above alloy. , The resulting mixture is heated and melted at an arbitrarily selected temperature to obtain a molten aluminum alloy. The Al source, Si source, Cu source, Mg source, Mn source, Fe source, Cr source, Ca source and Sr source may each be a single metal material, or an alloy material containing two or more kinds of metals. May be. The metal material used as a raw material may contain a large amount of Ca. In this case, the metal material as a raw material may be de-Ca-treated in advance so that the ratio Sr / Ca of the Sr content to the Ca content is within the above range. The temperature used for forming the molten metal can be arbitrarily selected.

(Casting process S02)
In the casting step S02, the cast product 1 (first cast product) is obtained by casting the aluminum alloy molten metal obtained in the molten metal forming step S01. FIG. 2 is a perspective view showing an example of an aluminum alloy (cast product) for sliding parts according to an embodiment of the present invention. In the casting step S02, as shown in FIG. 2, it is preferable to obtain a columnar cast product 1. There are no particular restrictions on the casting method. As a casting method, for example, a known method conventionally used as a casting method for an aluminum alloy such as a continuous casting and rolling method, a hot top casting method, a float casting method, and a semi-continuous casting method (DC casting method) can be used. Can be used. By this casting step, Mn forms fine granular crystallization containing an Al—Mn—Si intermetallic compound. Further, Fe forms fine crystals such as an Al—Fe—Si intermetallic compound, an Al—Cu—Fe intermetallic compound, and an Al—Mn—Fe intermetallic compound. Further, Cr forms a crystallized product as a fine Cr-containing intermetallic compound such as an Al—Fe—Cr intermetallic compound.

(Homogenization heat treatment step S03)
In the homogenization heat treatment step S03, the homogenization heat treatment is performed on the columnar cast product 1 obtained in the casting step S02. By this homogenization heat treatment, segregation of additive elements generated during casting is eliminated to homogenize the composition, and a hypersaturated solid solution generated by solidification during casting is precipitated, and further, semi-stable formed by solidification during casting. Phase change phase to equilibrium phase. The heating temperature in the homogenization heat treatment can be arbitrarily selected, and is, for example, in the range of 420 ° C. or higher and 500 ° C. or lower. If necessary, the temperature may be 430 ° C or higher and 480 ° C or lower, or 440 ° C or higher and 460 ° C or lower.

(Cut step S04)
In the cutting step S04, the columnar cast product 1 subjected to the homogenization heat treatment in the homogenization heat treatment step S03 is cut to a predetermined size to obtain a cast product for forging. That is, in the cutting step S04, the casting product 1 is cut along a flat surface to obtain a casting product for forging.

(Forging process S05)
In the forging step S05, the forging cast product obtained in the cutting step S04 is forged to obtain a forged product 2 (second cast product) having a desired shape. FIG. 3 is a perspective view showing an example of a sliding component (forged product) according to an embodiment of the present invention. The forged product 2 shown in FIG. 3 is a sliding component (scroll) for a scroll type compressor. The forged product 2 has a disk-shaped base portion 3 and a spiral-shaped protrusion portion 4. As the forging method, hot forging may be used or cold forging may be used. The heating temperature in hot forging can be arbitrarily selected, but is, for example, in the range of 350 ° C. or higher and 450 ° C. or lower. If necessary, the temperature may be 370 ° C or higher and 430 ° C or lower, or 390 ° C or higher and 420 ° C or lower.

(Solution processing step S06)
In the solution treatment step S06, the forged product 2 obtained in the forging step S05 is subjected to the solution treatment. By this solution treatment, elements such as Si, Cu, and Mg in the forged product 2 are re-dissolved in the aluminum alloy to generate a solid solution state. The heating temperature in the solution treatment can be arbitrarily selected, but is, for example, in the range of 450 ° C. or higher and 540 ° C. or lower. If necessary, the temperature may be 470 ° C or higher and 530 ° C or lower, or 490 ° C or higher and 510 ° C or lower.

(Quenching process S07)
In the quenching step S07, the forged product 2 which has been in a solid solution state in the solution treatment step S06 is subjected to a quenching treatment. By this quenching treatment, the forged product 2 is rapidly cooled to produce a supersaturated solid solution in which the solid solution state is maintained.
When the forging process is performed by hot forging in the forging step S05, the forging quenching is performed by using the heating during the hot forging without performing the solution heat treatment step S06. You may. Examples of the quenching process include water quenching.

(Aging treatment step S08)
In the aging treatment step S08, the forged product 2 which was the supersaturated solid solution in the quenching treatment step S07 is subjected to the aging treatment. By this aging treatment, the forged product 2 is tempered at a low temperature. By this aging treatment, clusters are formed in the aluminum alloy constituting the forged product 2, and Cu is precipitated with the clusters as nuclei to form G.I. P. Zones are created. Further, Mg forms a compound with Si and Cu and precipitates as a Q phase. The heating temperature in the aging treatment can be arbitrarily selected, but is, for example, in the range of 150 ° C. or higher and 220 ° C. or lower. If necessary, the temperature may be 170 ° C. or higher and 200 ° C. or lower, 180 ° C. or higher and 190 ° C. or lower. The heating time can be arbitrarily selected, and examples thereof include 0.5 hours to 20 hours and 1 hour to 16 hours.

(Shot peening step S09)
In the shot peening step S09, the forged product 2 that has been aged in the aging treatment step S08 is machined to prepare the surface or remove unprocessed parts, and then shot peened to the vicinity of the surface. Fatigue strength is improved by adding plastic working to. The size of the abrasive grains used in shot peening in which the abrasive grains collide with the alloy surface at high speed is preferably 1 mm or less. As the material of the abrasive grains, for example, stainless steel (eg, SUS304), alumina and the like can be used. The peening pressure is preferably 1 MPa or less.

By the above manufacturing method, sliding parts (forged products) can be manufactured. The obtained sliding parts had a tensile strength at 25 ° C. in the range of 330 MPa or more and 380 MPa or less, contained 1% by mass or more of Cu, and contained two crystallized compounds having a circle-equivalent diameter of more than 5 μm per 1182 μm ² . It does not contain the above, 2 or more Cr-containing intermetallic compounds having a length of 8 μm or more per 1182 μm ² , and does not contain 2 or more primary crystal Si grains having a circle-equivalent diameter of more than 10 μm per 4726 μm ² . This sliding component is excellent in tensile strength and formability of an alumite film. Therefore, this sliding component can form an alumite film having a Vickers hardness of 400 HV or more by anodizing. A sliding component provided with an alumite film having a Vickers hardness of 400 HV or more on this surface has higher tensile strength and wear resistance.

The aluminum alloy for sliding parts of the present embodiment having the above configuration contains each additive element of Si, Cu, Mg, Mn, Cr, Fe, Ca, and Sr within the above range, and the balance is Al. And unavoidable impurities, the tensile strength at 25 ° C. is in the range of 330 MPa or more and 380 MPa or less, the amount of Cu is 1% by mass or more, and the crystallized product having a circle-equivalent diameter of more than 5 μm is ² per 1182 μm 2. Since it is said that no more than two Cr-containing intermetal compounds having a length of 8 μm or more are contained per 1182 μm ² , the tensile strength and the formability of the alumite film are excellent.

Further, since the sliding component of the present embodiment is composed of the above-mentioned aluminum alloy for sliding component, it is excellent in tensile strength and formability of an alumite film. In the case of the sliding parts of the present embodiment, when they are forged products, the strength is further improved. Further, in the sliding component of the present embodiment, when the surface is provided with an alumite film having a Vickers hardness of 400 HV or more, the strength is further improved and the wear resistance is improved.

The sliding parts of this embodiment can be suitably used as sliding parts of a compressor (compressor). The forged product of the present embodiment can be advantageously used as a sliding component of a scroll type compressor, particularly as a sliding component of an electric scroll type compressor in which a swivel scroll is movable by a motor.

The present invention is not necessarily limited to that of the above embodiment, and various modifications can be made without departing from the spirit of the present invention.

Next, specific examples of the present invention will be described, but the present invention is not particularly limited to those of these examples.

<Example 1>
Si is 10.1% by mass, Cu is 1.0% by mass, Mg is 0.4% by mass, Mn is 0.4% by mass, Cr is 0.03% by mass, Fe is 0.19% by mass, and Ca is. Casting with a diameter of 82 mm by continuous casting of a molten aluminum alloy containing 0.0010% by mass and Sr at a ratio of 0.0010% by mass (Sr / Ca = 1.00) and the balance being Al. A product (first cast product) was obtained. The obtained cast product was subjected to a homogenization heat treatment, and then the cast product was air-cooled. Then, the cast product was cut to a predetermined length to obtain a cast product for forging. A forged product (second cast product) was obtained by hot forging the obtained cast product. The obtained forged product was subjected to a solution treatment and then a water quenching treatment. Next, the cast product after the water quenching treatment was subjected to an aging treatment to obtain a forged product for sliding parts.

<Examples 2 to 5 and Comparative Examples 1 to 15>
The same as in Example 1 except that the contents of Si, Cu, Mg, Mn, Cr, Fe, Ca, and Sr of the aluminum alloy (containing unavoidable impurities) were changed to the ratios shown in Table 1. A forged product for sliding parts was obtained.

[evaluation]
The forged products for sliding parts obtained in Examples 1 to 3 and Comparative Examples 1 to 15 were evaluated as follows.

<Composition>
The content of each element of Si, Cu, Mg, Mn, Cr, Fe, Ca and Sr of the forged product for sliding parts was measured as follows. The forged product for sliding parts is dissolved with hydrochloric acid and hydrogen peroxide. The content of each element in the obtained solution is measured using an ICP emission spectroscope, and the measured value is converted into the content of each element in the forged product.
As a result of this measurement, the content of each element of the forged products obtained in each Example and Comparative Example was the same as the content shown in Table 1.

<Tissue observation>
The structure of the forged product for sliding parts was observed as follows.
A forged product for sliding parts is cut out to a predetermined size to prepare an observation sample. A surface parallel to the forging direction of the observation sample is processed into an observation surface to obtain an observation surface. The observation surface of the observation sample is observed using FE-SEM / EDS. The magnification of FE-SEM is set to 3000 times, and elemental analysis is performed using EDS with respect to the observation field of FE-SEM (30.47 μm × 38.79 μm = 1182 μm ² ) to obtain 1% by mass of Cu. The Cu-based crystallized product containing the above and the Cr-containing metal-to-metal compound are specified. For the specified Cu-based crystallized material, the diameter equivalent to a circle is calculated, and the "number of Cu-based crystallized materials having a diameter equivalent to a circle exceeding 5 μm" and the "diameter equivalent to a maximum circle" are obtained. The length of the specified Cr-containing intermetallic compound is calculated, and the "number of Cr-containing intermetallic compounds having a length of 8 μm or more" and the "maximum length" are obtained. In addition, the magnification of FE-SEM is set to 1500 times, and elemental analysis is performed using EDS for the observation field of view of FE-SEM (60.9 μm × 77.6 μm = 4726 μm ² ), and primary crystal Si. Identify the grain. The diameter equivalent to a circle is calculated for the specified primary crystal Si grains, and the "number of primary crystal Si grains having a diameter equivalent to a circle exceeding 10 μm" and the "diameter equivalent to a maximum circle" are obtained. Observation of Cu-based crystallized products, Cr-containing intermetallic compounds, and primary crystal Si grains was performed on four observation surfaces. "Number of Cu-based crystals having a circle-equivalent diameter of more than 5 μm", "Number of Cr-containing intermetallic compounds having a length of 8 μm or more" and "Number of primary crystal Si grains having a circle-equivalent diameter of more than 10 μm" are It is the average value of the number measured in those observation planes. Further, the "maximum circle-equivalent diameter" of the Cu-based crystallized product and the primary crystal Si grain and the "maximum length" of the Cr-containing intermetallic compound are the maximum values measured in their observation planes. The results are shown in Table 2.

<Tensile strength>
The tensile strength of the forged product for sliding parts was measured as follows.
A forged product for sliding parts is cut out to a predetermined size to prepare a JIS No. 4 tensile test piece. The obtained JIS No. 4 tensile test piece is subjected to a tensile test in accordance with the provisions of JIS Z2241: 2011 (metal material tensile test method), and the tensile strength (MPa) at 25 ° C. is measured.
The results are shown in Table 2. In Table 2, those having a tensile strength within the range of 330 MPa or more and 380 MPa or less are described as "○ (possible)", and those having a tensile strength outside the above range are described as "x (impossible)". bottom.

<Hardness of alumite film>
The forged product for sliding parts was anodized to form an alumite film having a thickness of 20 μm on the surface of the forged product. Then, the hardness of the obtained alumite film was measured.
The alumite film was formed as follows. The forged product is immersed in an electrolytic solution having a free sulfuric acid concentration of 150 g / L and a liquid temperature of 5 ° C. Next, using the forged product as an anode, a current having a current density of 3 A / dm ² is passed to form an alumite film on the surface of the forged product. Then, the forged product on which the alumite film is formed is taken out from the electrolytic solution, and the alumite film is mirror-finished by buffing.
The hardness of the alumite film was measured as follows. The hardness of the alumite film is measured using a Vickers hardness tester. The hardness is measured in the thickness direction of the alumite film, and the load is 0.01 g.
The measurement results are shown in Table 2. In Table 2, those having a Vickers hardness of less than 400 HV are described as "x (impossible)", and those having a Vickers hardness of 400 HV or more are described as "○ (possible)".

<Comprehensive evaluation>
If the tensile strength was "○ (possible)" and the hardness of the alumite film was "〇 (possible)", the comprehensive evaluation was passed ("○"). If there was an "x (impossible)" in either the tensile strength or the hardness of the alumite film, the overall evaluation was rejected ("x"). The results are shown in Table 2.

From the results in Table 2, the content of each additive element of Si, Cu, Mg, Mn, Cr, Fe, Ca, Sr, the crystallized product containing 1% by mass or more of Cu, the Cr-containing intermetallic compound, and the primary crystal Si It was confirmed that the forged products of Examples 1 to 5 in which the amount of the precipitates such as grains mixed in were within the range of the present invention were excellent in both the tensile strength and the hardness of the alumite film. On the other hand, in Comparative Examples 1 to 14 in which the content of each additive element and the amount of the precipitate mixed out of the range of the present invention, at least one of the tensile strength and the hardness of the alumite film was insufficient. ..

The present invention provides an aluminum alloy for sliding parts and sliding parts having excellent strength and formability of an alumite film. The sliding component made of an aluminum alloy for sliding components according to the present invention can be suitably used as a sliding component of a compressor (compressor) for an automobile air conditioner, particularly a sliding component of a scroll type compressor or an electric scroll type compressor. ..

1 Casting 2 Forged 3 Base 4 Protrusions

Claims

Si is in the range of 8.0% by mass or more and 12.0% by mass or less, Cu is in the range of 0.8% by mass or more and 1.1% by mass or less, and Mg is in the range of 0.4% by mass or more and 0.6% by mass or less. Mn is in the range of 0.30% by mass or more and 0.60% by mass or less, Cr is in the range of 0.01% by mass or more and 0.03% by mass or less, and Fe is in the range of 0.10% by mass or more and 0. Ca is contained in the range of 30% by mass or less, Ca is contained in the range of 0.0005% by mass or more and 0.0050% by mass or less, Sr is contained in the range of 0.00005% by mass or more and 0.03000% by mass or less, and the balance is Al. And unavoidable impurities
The ratio of Sr content to Ca content Sr / Ca is in the range of 0.01 or more and 30 or less.
The tensile strength at 25 ° C. is in the range of 330 MPa or more and 380 MPa or less.
It contains 1% by mass or more of Cu and does not contain 2 or more crystallizations having a diameter equivalent to a circle exceeding 5 μm per 1182 μm 2 .
An aluminum alloy for sliding parts, characterized in that it does not contain two or more Cr-containing intermetallic compounds having a length of 8 μm or more per 1182 μm 2 .
The aluminum alloy for sliding parts according to claim 1, which does not contain two or more primary crystal Si grains having a diameter equivalent to a circle exceeding 10 μm per 4726 μm 2 .
Sliding parts made of the aluminum alloy for sliding parts according to claim 1 or 2.
The sliding part according to claim 3, which is a forged product.
The sliding component according to claim 3 or 4, wherein the surface is provided with an alumite film having a Vickers hardness of 400 HV or more.
The sliding component according to any one of claims 3 to 5, which is a sliding component of a compressor.
The sliding component according to any one of claims 3 to 5, which is a sliding component of a scroll type compressor.
The sliding component according to any one of claims 3 to 5, which is a sliding component of an electric scroll type compressor.
The aluminum alloy for sliding parts according to claim 1, which contains Si in an amount of 8.5% by mass or more and 12.0% by mass or less.